This application claims priority to a Taiwan application No. 098101711 filed Jan. 16, 2009.
1. Field of the Invention
The invention relates to an optical sensing module and an optical mouse with the same, and more particularly, to an optical sensing module with assembly preciseness easier to be improved and an optical mouse with the same.
2. Description of the Related Art
FIG. 1 is a schematic cross-section view illustrating a conventional optical mouse. Referring to FIG. 1, the optical mouse 100 comprises a shell 11 and an optical sensing module 10 disposed in the shell 11. The optical sensing module 10 comprises a printed circuit board 12, a packaging body 14, a lens unit 15, a printed circuit board rack 16 and a bottom plate 17 connected to the shell 11. The printed circuit board 12 of the optical sensing module 10 has an upper surface 122, a lower surface 124 and a through hole 126. The upper surface 122 and the lower surface 124 are opposite to each other, and the through hole 126 passes through the upper surface 122 and the lower surface 124. The packaging body 14 is disposed above the through hole 126.
The packaging body 14 comprises a compound 140, an optical sensing die 146 and a lead frame 148. The optical sensing die 146 is packaged in the compound 140. The lead frame 148 is electrically connected with the optical sensing die 146 and extends through the side surface 144 of the compound 140 and out thereof. The packaging body 14 is positioned on the upper surface 122 of the printed circuit board 12 by the transparent surface 142 of the compound 140. The portion of lead frame 148 outside the compound 140 is bended toward and inserted through the printed circuit board 12 from the upper surface 122 to the lower surface 124 and welded thereon by the solder 13. The lens unit 15 is disposed under the through hole 126 and fixed on the bottom plate 17. The printed circuit board rack 16 is disposed between the printed circuit board 12 and the bottom plate 17.
As shown in FIG. 1, the light 110 reflected from the object, which, for example, is a mouse pad, contacted to the bottom of the optical mouse 100 into the optical mouse 100 may be focused on the optical sensing die 146, thus the moving locus of the optical mouse 100 would be recorded as a set of continue pictures shotted in high speed. The moving direction and the distance of the optical mouse 100 may be determined by analyzing the changes between the positions of the characteristic points in the pictures. Therefore, the positioning of the cursor may be achieved.
However, in the assembling process of the optical mouse 100, the accuracy of the interval D between the optical sensing die 146 and the lens unit 15 predetermined according to the focal length of the lens unit 15 may be affected by the error resulted from the deformation of the compound 140, the height error of the optical sensing die 146 disposed in the compound 140, the thickness error of the printed circuit board 12 and the height error of the printed circuit board rack 16, thus the light unsuccessfully focus on the optical sensing die 146. Accordingly, the problem of decreasing the assembling error and improving preciseness of assembling for raising the accuracy of focusing light to the optical sensing die 146 is one of the issues attended by those skilled in the related fields.